The purpose of this continuing effort is to improve the method of quantitating the severity of life-threatening injuries and disease states and to assess the effectiveness of the patient care system. In these investigations by an interdisciplinary group of clinicians, biomathematicians, engineers and computer scientists, a comprehensive inventory of hemodynamic, respiratory and metabolic status of the patient is obtained. Together with the clinical history and physical findings, this data base is first utilized to assign the patient to a clinical category of acute illness. The major objective of this project is the development and improvement of an indicator of prognosis based on successive determinations of patient status. Both momentary and accumulative prognostic indices are obtained. These indices provide a measure of the effectiveness of clinical management, serve to indicate need for priority assignment of patients to critical care units, and supplement bedside alarm systems for detecting medical crises. By identifying primary disturbances and severity, the extensiveness of monitoring optimized with view to minimizing invasiveness, technical complexity, and cost of routine monitors. Quantitation of the severity of the patient's illness on admission to the critical care system as well as the ultimate survival or fatal outcome serve as measures of effectiveness of medical care. With studies based on populations of patients with comparable severity of illness, within or between hospitals, we would be in a position to quantitate those facilities and ingredients of professional care which are life-determining.